Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
12 Cards in this Set
- Front
- Back
|
SPECIES DEFINITION |
A species is a group of individuals that share many characteristics and are able to interbreed under natural conditions to produce fertile offspring. |
|
|
EVOLUTION DEFINITION |
Evolution is the gradual process of change in the inherited traits of a population of organisms from one generation to the next |
|
|
POPULATION DEFINITION |
A population is a group of the same species living together in a particular place at a particular time. When studying a species, geneticists prefer to consider the characteristics of a population as a whole, rather than the individual organism - they are interested in the gene pool. |
|
|
GENE POOL DEFINITION |
A gene pool is the sum of all the allele in a given population. |
|
|
CHANGES TO ALLELE FREQUENCIES |
- Mutations - Natural Selection - Random Genetic Drift - The Founder Effect - Migration |
|
|
MUTATIONS DEFINITION |
A mutation is defined as new variations in offspring which show no resemblance to either parent. Mutations may occur quite suddenly and purely by chance. An organism with a characteristic that results from a mutation is called a mutant. |
|
|
TWO TYPES OF MUTATIONS |
1. Gene mutations: changes in the DNA of a single gene whereby the traits normally roduced by that gene are destroyed and replaced with the mutation. 2. Chromosomal mutations: all or only part of a chromosome is affected. |
|
|
CELLS AFFECTED BY MUTATIONS |
1. Somatic Cells: the body cells - only the characteristic of the individual with the mutation is affected - cannot be passed onto next generation. Mutation is lost when the affected individual dies. 2. Germline Cells: affects the gametes - genetic information is passed onto the next generation - results in a change to allele frequencies - person whose cells are mutated usually goes unaffected just their offspring. |
|
|
NATURAL SELECTION DEFINITION |
A situation in which nature favours one characteristic for survival at the expense of others, to give the species some kind of survival advantage. Natural selection is not a random event. Alleles passed on from one generation to the next cause a survival advantage. |
|
|
RANDOM GENETIC DRIFT |
Genetic drift describes totally random, non-directional fluctuations in allele frequencies in a population. Genetic drift takes place when the frequency of alleles increases and decreases by chance over time. Occurs most commonly in small populations. An allele that is rare in large populations may, purely by chance, become frequent in small populations. |
|
|
EXAMPLE - RANDOM GENETIC DRIFT |
The Dunkers The Dunkers are an isolated population from Hesse Germany who emigrated and live in the town of Pennsylvania. Due to their religion, they are not allowed to marry outside of their religious group (Hence, a small, isolated population in a larger population). They were tested on common traits like ABO blood frequency, Rh and MN blood groups, mid digital hair, left and right-handedness as well as attached and free earlobes. Results shows random genetic drift - the Dunkers varied in allele frequency from the Hesse population, nor the US population in which they lived - Random variation occurred. |
|
|
THE FOUNDER EFFECT |
A founder effect occurs when a part of a population moves to a new locale and a new colony is started by a few members population. This small population size means that the colony may have: - reduced genetic variation from the original population. - a non-random sample of the genes in the original population. |
